Having a series of common dilemmas handy allows you to specify how character x differs from character y e.g.
The character you are developing was really hungry last night but short on cash. They went to the refrigerator and found a slice of pie belonging to their flatmate. What do they do?
If they eat it do they scarf it quickly stood by the fridge terrified of being caught? Or do they eat it sensibly? Do they even get a kick out of the act of theft?
It's the next day, their flatmate discovers that their pie slice is missing. They ask loudly who stole their pie. How does character x react?
Do they admit to their crime? If so how do they explain their actions to their angered flatmate? Do they make a concrete promise to replace the missing pie? Do they intend to follow through if they do?
The purpose in running the character through these simple diagnostic actions is to find out whether the character would cheat. And if they would cheat how they would deal with the situation.
Cheating is something human beings are attuned to be interested in and to consider carefully. A psychological experiment called the Wason Selection test shows how human beings find it easier to deal with logic tests when they are contextualised as being about people cheating or betraying social norms than when they are presented as dry facts. People are built to think about cheating and cheaters. So to find the measure of a person, or aid yourself in considering their character it is likely to help if you think about how they would cheat, whether they would cheat and how they would react if they were caught.